Cornus kousa tree designated &#39;Rutpink&#39;

ABSTRACT

A new  Cornus kousa  cultivar that is clearly distinguished by its floriferous display of showy, dark-pink floral bracts, attractive dark-green foliage, high level of winter hardiness, and tolerance of the incitants of powdery mildew.

CROSS REFERENCE TO RELATED APPLICATIONS

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STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

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Latin name of genus and species of the plant claimed: Cornus kousaBuerger×Miq.

Variety denomination: Rutpink.

DESCRIPTION

Botanical designation: Cornus kousa Buerger ex Miq.

Variety denomination: ‘Rutpink’.

BACKGROUND OF THE INVENTION

This new cultivar is the product of a long standing program ofhybridization and selection of big-bracted dogwoods, in this instancethe result of an open-pollination event of an unnamed pink-bractedCornus kousa tree held in the germplasm collection at a New Jerseyuniversity. The purpose of the program was to develop new and superiorcultivars of dogwoods expressing consistently dark-pink floral bractsthat are cold hardy in New Jersey and similar climates. The seed parentof this new cultivar is a pink-bracted, unreleased breeding selectiondesignated as K187-44 which resulted from a cross of Cornus kousa‘Satomi’ and C. kousa ‘Benifuji’ made in 1996 by Dr. Elwin Orton. Themale (pollen) parent is unknown but from a limited breeding block ofimproved dogwood trees existing in an isolated area. The progeny fromwhich the plant in question was selected were analyzed for theirdifferences and outstanding value as potential commercial cultivars.

We selected the particular seedling hereof from certain progeny grown ina cultivated area, and as a result, have in turn caused the same to beasexually reproduced by budding, grafting, and micropropagation (planttissue culture). The reproduction and actual growth and selection of thenew cultivar took place in the vicinity of New Brunswick, N.J. Theclaimed cultivar is stable and reproducible true-to-type in successivegenerations of asexual reproduction.

As will be understood from the detailed description of the inventionwhich appears hereinafter, the new cultivar is in fact outstanding andreadily identified as being such. With the foregoing in mind, thedescription which follows will be understood as clearly defining the newcultivar, the desirable characteristics of which are the result of sucha program as has been heretofore stated.

SUMMARY OF THE INVENTION

The cultivar, designated here as ‘Rutpink’, originated in cultivatedfield #3 at a horticultural farm at said New Jersey university in NewBrunswick, Middlesex County, N.J., 08901. This seedling originallyresulted from an open-pollination event in 2008 of a Cornus kousa treedesignated K187-44, which is located in Row 4, tree 39 in Field 70 atthe university's research and extension farm in Adelphia, N.J.

The seedling, which became this new cultivar, germinated in February2009, was transplanted to progressively larger containers, and wasfinally transplanted to the field in September 2009 at said horticulturefarm in New Brunswick, New Jersey. Five grafts were made of this tree inMarch 2013 and two were subsequently field planted at the same farm inSeptember 2014 for further observation along with the original seedling.The plant was also propagated by budding onto C. kousa and C. floridaseedling rootstock in August 2013 in Belvidere, Tennessee, 37306 andBoring, Ore., 97009, and was subsequently evaluated in those regions forpropagation performance, powdery mildew response, growth habit and leafquality, and floral bract color in 2015 in TN.

The dogwood tree of the present invention is asexually propagated bygrafting (usually T-budding or chip-budding but also side-veneergrafting), by softwood cuttings, or via meristem culture (plant tissueculture). It is distinguished from patented and/or commerciallyavailable cultivars of pink-bracted Cornus kousa or C. florida×C. kousahybrids in the following respects:

A group of five pink-bracted Cornus kousa cultivars widely available inthe nursery trade includes ‘Satomi’(also called ‘Miss Satomi’),‘Rosabella’, ‘Rosea’, ‘Schmred’ (Heart Throb®, expired U.S. Plant Pat.No. 9,283), and ‘Hanros’ (Radiant Rose). These five cultivars are verysimilar to one another in terms of mature floral bract shape and colorand are clearly different than autpink'. It should be noted thatTrigiano et al. (2004) showed that when using molecular markers,‘Rosabella’, ‘Satomi’, and ‘Schmred’ (Heart Throb®, had nearly identicalfingerprints suggesting they are the same cultivar or are full-siblingsof one another. The five cultivars have mature floral bracts that areovate to obtuse in shape (Cappiello and Shadow, 2005), whereas ‘Rutpink’has floral bracts that are distinctly acuminate as clearly describedhereinafter. The floral bracts of ‘Rutpink’ are also generally larger insize than these five cultivars when measured from the tip of oneopposing floral bract to the other at the time of anthesis. Further,under New Jersey conditions in late May to early June when airtemperatures can reach over 85 degrees Fahrenheit (26.7 Celsius), floralbract color in full sun at the time of anthesis for the five availablecultivars is generally light pink to cream color with an uneven shading(typical base color of floral bracts is 36 C and 36 D Red Group basedupon The Royal Horticultural Society (R.H.S.) Colour Chart (1966) withintermittent splotches of 49 A Red Group and edges of floral bractssometimes reaching 50 B Red Group). In contrast, the floral bracts of‘Rutpink’ remain uniform in color and are generally much darker pink,with the color most closely approximated by 54 A and 54 B Red Group,with a majority of the bracts 54 B Red Group. Further, ‘Rutpink’ has adistinct reflective quality of the floral bracts that display abrilliant pink color on a landscape level. This is lacking in the othercultivars which, under hot New Jersey air temperature conditions, appearcream colored to very pale pink at a distance.

‘Benifuji (expired U.S. Plant Pat. No. 8,676) differs from ‘Rutpink’ dueto its smaller floral bracts at the time of anthesis, which averagearound 8-9 cm when measured from the tip of one opposing floral bract tothe other whereas ‘Rutpink’ averages over 13 cm. Further, the time ofanthesis of ‘Benifuji’ is regularly about 5-7 days later than ‘Rutpink’and, under New Jersey conditions, the floral bracts of ‘Benifuji’ areconsistently lighter pink although generally darker than the fivecultivars referenced above.

‘KN144-2’ Rosy Teacups™ (Plant patent pending) differs from ‘Rutpink’ inthe upward growth and development of its young floral bracts up untilaround the point of anthesis. Also, the bracts of ‘KN144-2’ are slightlylarger and ovate in shape with a slight overlap of the basal 30% of thelength of neighboring bracts, whereas ‘Rutpink’ has distinctly acuminatefloral bracts with less than 10% overlapping of neighboring bracts attheir base at anthesis. The floral bracts of ‘Rutpink’ are alsogenerally a darker pink color at anthesis in New Jersey.

‘Rutgan’ (Stellar Pink®; expired U.S. Plant Pat. No. 7,207) is aninterspecific hybrid between Cornus florida and Cornus kousa, which hassmaller floral bracts than ‘Rutpink’ that are nearly rounded to obovatein shape with short, acute tips and tapered bases that are moreoverlapping. ‘Rutgan’ blooms around two weeks before ‘Rutpink’,indicative of its hybrid background, with an anthesis date between thatof the earlier blooming Cornus florida and the later blooming(approximately 1 month) Cornus kousa. ‘Rutgan’ is also sterile,producing no mature fruit, whereas ‘Rutpink’ produces abundant fruitwith fertile seeds.

BRIEF DESCRIPTION OF THE DRAWINGS

This new cultivar of dogwood is illustrated by the accompanying digitalphotographs, depicting defining characteristics of the plant by the bestpossible color representation using digital color photography. All colorreferences herein are measured against said Royal Horticultural Society(R.H.S.) Colour Chart (1966). Colors are approximate as individual colordepends on horticultural practices such as light level, temperature, andfertilization rate, among others.

FIG. 1 shows four images of a dogwood tree of the present invention atpeak floral display after 7 growing seasons. Multiple images are shownto present the different floral bract color displays depending on thelevel of sunshine, distance from tree, and angle of viewing. From leftto right top to bottom: (A) photograph taken from ground level on abright, sunny day; (B) photograph taken from ground level on a cloudyday; (C) photograph taken at a distance of 8 meters from tree on abright, sunny day; and (D) photograph taken from an elevated position (4meters) on bright, sunny day.

FIG. 2 shows four images representing close-up views of individualflower heads at peak ornamental display or shortly after. Note that theimages show the distinctly acuminate floral bracts. From left to righttop to bottom: (A) photograph taken in full sun on date of peak floraldisplay prior to true flowers opening; (B) photograph taken out ofdirect sunlight on date of peak floral display; (C) photograph taken outof direct sunlight and next to R.H.S. Colour Chart card Red Group 54 forbract color comparison; and (D) photograph taken several days after peakfloral display. Floral bracts fade to a lighter pink color once trueflowers are open.

FIG. 3 shows two digital images that represent the high density offlower heads per branch, which is a defining characteristic of‘Rutpink’. The top image (A) was taken on a bright, sunny day at peakfloral display. The bottom image (B) was taken on a cloudy day severaldays after true flowers opened. Note in the second image the floralbracts are slightly wider and the color is a lighter pink.

FIG. 4 shows two digital images that represent the color and shape ofmature fruit, which is consistent with the species. The top image (A)shows fruit that have just reached maturity. The lower image (B) showsolder fruit that are beginning to senesce (soften), as well as a typicalrepresentation of fall leaf color.

BOTANICAL DESCRIPTION OF THE INVENTION

-   Form: Tree. Growth habit: Dense tree branched low to ground with    upright branches which form a rounded, but spreading, head. Vigorous    but compact, and slightly taller than wide.-   Height: 3.20 meters at 7 years. Spread: 2.50 meters at 7 years.    Plant vigor is similar to the species.-   Cold hardiness: The original seedling, and five grafted propagules    thereof, have suffered no visible winter injury to vegetative or    floral buds during the 6 and 2 winters since 2009 and 2013,    respectively, that the plants have been under test in the field at    New Brunswick, New Jersey, in USDA Plant Hardiness Map Zone 6a (−5    degree. to −10 degree F.).-   Resistance to insects and diseases: No evidence of insect problems    has been observed on the original seedling, or its propagules, in    the years the plants have been under test in New Jersey, Tennessee,    and Oregon. An inconsequential amount of powdery mildew was observed    on the original seeding plant in the year 2012 and 2014 in New    Jersey and a small amount in 2014 in Tennessee on late season    vigorous growth with none reported from Oregon. No evidence of    susceptibility to Dogwood anthracnose or common dogwood borer has    been presented.-   Trunk: Circumference of the trunk at 10 cm above the soil level was    29 cm after 7 growing seasons. Texture: Smooth, although some parts    sandpaper rough due to presence of lenticels.-   Color of bark on trunk and main scaffold branches: Closest to 197A    and 197B Greyed Green Group. Younger stems (1 and 2 years) closest    to 200 C and 200 B Brown Group. Three-year-old branches closest to    197A and 197B Greyed Green Group and sandpaper rough due to the    presence of lenticels (average 15-20 per cm²). Lenticels are closest    to 156 B Greyed White-   Group. Size of lenticels is 1.0-2.0 mm long by 0.3 mm-0.4 mm wide.    Lenticels are present on younger stems but are less than 1.0 mm    long, same color.-   Branches: Crotch angle 35-55 degrees for large, major branches, but    45-70 degrees for subsequent smaller branches.-   Foliage:-   Leaf arrangement: Opposite. Leaf size: Lamina. Average length: 96.7    mm (range 76-115; n=50). Average width: 55.8 mm (range 41-76, n=50),    the widest point being a little more than half-way down from the    tip. Petiole: Average length 6.4 mm (range 3-12 mm, n=50).-   Shape: Ovate/elliptic. Tip: Acuminate. Base: Rounded. Number of    pairs of veins: 4 to 5. Margin: Moderately wavy with some leaves    slightly folded towards adaxial side along mid vein.-   Texture: Adaxial surface is smooth. The abaxial surface is slightly    fuzzy due to many minute trichomes on the blade and tufts of longer,    thin hairs in clumps along the midrib and the secondary veins,    especially at the junctures of the midvein and 4^(th) and 5^(th)    pairs of secondary veins.-   Quantity: Many, densely foliaged.-   Coloration: Solid.-   Mature leaf color: Adaxial: Closest to 137A-B Green Group. Abaxial:    Closest to 138 B Green Group. The color of the lower one third of    the mid vein on the adaxial side is 59 A Red-purple group. The same    color also extends to the lower one third of the 4th or 5th    secondary veins closest to the petiole. The color of the mid vein on    the abaxial side is 160 D Greyed Yellow group with most secondary    veins 59 A Red-Purple Group. Petiole: Closest to 59 A Red Purple    group.-   Immature leaf color: Adaxial: leaf surface areas closest to the    veins are 144 A Yellow Green Group and in the regions between veins    187 A to 187 B Greyed Purple group. Veins are 59 A Red-Purple Group.    Abaxial: mostly 146 C Yellow-green group with some interveinal    splotches of 187 A Greyed Purple Group. Petiole is closest to 59 A    Red-purple group.-   Autumn foliage color (mid-October), New Brunswick, N.J. Adaxial    surface: Most leaves 137A Green Group but mottled with other colors    (mostly 187A Greyed-Purple Groups, 183A Greyed-Purple Group, 53A Red    Group, 46A Red Group, 43A Red Group, and 9A Yellow Group). Abaxial    surface: 138A Green Group. Leaf color is dependent on many    environmental factors such as soil type, exposure to sun, air    temperature, day length, available water and nutrients. Thus, leaf    color may vary from one area to another.-   Inflorescence:-   Location where observations were made: New Brunswick, N.J. Type of    inflorescence: Flower head. Dense, rounded mound. Peduncle size    (late May at time of anthesis): Average length (n=50): 78.7 mm cm    (range=63 mm to 110 mm). Average width (n=20): 1.4 mm (range=1.2    cm-1.7 cm).-   Floral bracts:-   Number: Four (two opposing pairs, lower and upper).-   Size of floral bracts at time of floral period late May to early    June:

TABLE 1 Lower floral bract dimensions; n = number of measurements. Lowerbract n = 50 for all measurements Average length Average WidthInvolucral spread (mm) (mm) (mm) 67.3 35.2 134.5

TABLE 2 Upper floral bract dimensions; n = number of measurements. Upperbract n = 50 for all measurements Average length Average WidthInvolucral spread (mm) (mm) (mm) 66.4 31.9 133.6

-   The average length of the lower and upper bracts is very similar in    size with the lower bracts being just slightly larger on average.    The average width of the lower bracts is consistently larger than    the upper bract. Bract length and width will vary slightly from    year-to-year based on environmental conditions and flower head    numbers within the tree canopy, but the relationship between the    size of the upper and lower bracts and the ratio of length to width    across all bracts remains consistent.-   Shape: The individual floral bracts are distinctly acuminate with    their apices terminating in a long, thin point. They are obtuse to    rounded at their base. For most flower heads, bracts overlap their    adjacent partner bract less than 10% of their total width at    anthesis. Younger bracts show no overlap.-   Color: At peak of floral display (approximately May 28 to June 2 in    New Brunswick, N.J.) in full sun exposure: Adaxial: Closest to and    in between 54 A and 54 B Red Group, most being 54 B. Abaxial:    Closest to 51 C Red Group with some visible veins the color of 51 B    Red group. Peduncle of flower head at peak floral display is 144 C    Yellow Green group. Floral bract color lightens (closest to 55 D Red    Group) after anthesis and prior to dropping of the bracts.-   Flower description: Very floriferous. Single flowers arranged in    compact, dense heads subtended by the large floral bracts. The    average number of true flowers per flower head is 42, ranging from    38 to 46 (n=20). No observed fragrance. Flowers are not persistent.    Floral display of the involucral bracts typically lasts about three    weeks depending on weather conditions.-   Flowering habit: Anthesis of the tiny, relatively inconspicuous true    flowers generally begins around the time of peak ornamental display    of the floral bracts (approximately May 28 to June 2 in New    Brunswick, N.J.). The color of the floral bracts lightens after    anthesis.-   Reproductive organs:-   Stamens per flower: 4.-   Filament: Length: approximately 2.75 mm (n=4). Width: approximately    0.28 mm (n=4). Color: 155B White Group.-   Anther: Length: approximately 0.4 mm (n=4). Width: approximately    0.81 mm (n=4). Color: 162A Greyed-Yellow Group. Pollen: Color of    freshly dehisced pollen is approximately 158 A Yellow white group.-   Style: Height: approximately 1.5 mm (n=4). Width: approximately 0.3    mm (n=4). Color: 144 C Yellow-Green Group.-   Stigma: Height: approximately 0.25 mm (n=4). Width: approximately    0.5 mm (n=4). Color: 144 C Yellow-Green Group. All figures are based    on an average of the 4 measurements.-   Fruit:-   Flower head with mature fruit. Fruits are 2-celled, typically    1-seeded, fleshy drupes that form a mounded, raspberry-like syncarp    averaging 23.2 mm in length, 22.3 mm in width, and 21.0 mm in height    (n=56). The many ovaries are enclosed in a fleshy, rounded mass    typical for fruit of Cornus kousa. The exterior of the aggregate    fruit is fairly smooth except for the dried floral parts at the tip    of each individual drupe (the dried remains of the sepals and the    persistent style and stigma).-   Fruit color varies from green to yellow to orange to pink as the    fruit matures and finally to 46A to 42C Red Group. Fruits ripen in    late August and persist for around 6 weeks.-   Seed: Color when dry: Closest to 165 C to 165 D Greyed Orange Group.    Size: Average 6.4 mm length, 4.8 mm width, and 3.6 mm in thickness    (n=40). Shape: typical for Cornus kousa. Average number of seeds per    fruit is 16 (n=36).

What is claimed is:
 1. A new and distinct cultivar dogwood tree, substantially as herein shown and described, comprising an advanced generation seedling of Cornus kousa with dark-pink colored floral bracts. 